WO2021177382A1

WO2021177382A1 - Positive electrode material and battery

Info

Publication number: WO2021177382A1
Application number: PCT/JP2021/008285
Authority: WO
Inventors: 健太長嶺; 出佐々木; 西山　誠司
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2020-03-05
Filing date: 2021-03-03
Publication date: 2021-09-10
Also published as: US20220393168A1; EP4117054A1; JPWO2021177382A1; EP4117054A4; CN115136349A

Abstract

A positive electrode material 1000 according to the present disclosure contains a material 100 which is represented by composition formula (1) and a carbon material 101 which is capable of adsorbing at least one substance that is selected from the group consisting of elemental halogens and halides.　Formula (1): LiaMbXc In the formula, each of a, b and c represents a number larger than 0; M includes at least one element that is selected from the group consisting of metal elements other than Li and semimetal elements; and X includes a halogen element.

Description

Positive electrode material and battery

The present disclosure relates to a positive electrode material for a battery and a battery.

Patent Document 1 discloses a battery using a positive electrode containing a lithium-containing metal oxide and a negative electrode containing a carbon material.

Patent Document 2 discloses a solid electrolyte material containing lithium, yttrium and halogen.

Patent No. 1989923 International Publication No. 2018/025582

The present disclosure provides a novel positive electrode material.

The positive electrode material in one aspect of the present disclosure is
The material represented by the following composition formula (1) and
A carbon material capable of occluding at least one selected from the group consisting of elemental halogens and halides,
including.
Li _a M _b X _c・・・ Equation (1)
Here, a, b, and c are values larger than 0, respectively.
M contains at least one selected from the group consisting of metallic elements other than Li and metalloid elements.
X contains a halogen element.

According to the present disclosure, a new positive electrode material can be provided.

FIG. 1 is a cross-sectional view showing a schematic configuration of a positive electrode material according to the first embodiment. FIG. 2 is a cross-sectional view showing a schematic configuration of the battery according to the second embodiment. FIG. 3 is a graph showing the charge / discharge curves of the batteries of Examples 1, 2 and 3. FIG. 4 is a graph showing the charge / discharge curves of the batteries of Reference Examples 1 and 2. FIG. 5 is a graph showing the charge / discharge curves of the batteries of Examples 4, 5, 6 and 7. FIG. 6 is a graph showing the charge / discharge curves of the batteries of Examples 4, 8 and 9. FIG. 7 is a graph showing cyclic voltammograms of the batteries of Examples 9, 10 and Reference Example 2. FIG. 8 is a graph showing the results of Raman spectroscopic measurement of the positive electrode material of the battery of Example 11 before the charge test, after the charge test, and after the discharge test.

(Summary of one aspect of the present disclosure)
The positive electrode material according to the first aspect of the present disclosure is
The material represented by the following composition formula (1) and
A carbon material capable of occluding at least one selected from the group consisting of elemental halogens and halides,
including.
Li _a M _b X _c・・・ Equation (1)
Here, a, b, and c are values larger than 0, respectively.
M contains at least one selected from the group consisting of metallic elements other than Li and metalloid elements.
X contains a halogen element.

According to the first aspect, a new positive electrode material can be provided. In the battery containing this positive electrode material, the charge / discharge reaction proceeds by a new mechanism. This positive electrode material is suitable for improving the output of the battery.

In a second aspect of the present disclosure, for example, in the positive electrode material according to the first aspect, in the Raman spectrum of the carbon material, to the intensity I _G of the peak appearing at 1500 cm ^-1 or 1700 cm ^-1 in the range, 1300 cm ^-1 above 1400 cm ^-1 ratio I _D / I _G of the intensity I _D of the peak appearing in the range may be 0 to 2. According to the second aspect, the carbon material can more easily occlude the halogen simple substance or the halide.

In the third aspect of the present disclosure, for example, in the positive electrode material according to the first or second aspect, the BET specific surface area of the carbon material may be larger than ^{5 m 2} g ^-1. According to the third aspect, the area where the carbon material and the material represented by the composition formula (1) are in contact with each other is large. Thereby, the current density of the battery including the positive electrode material can be improved. In addition, the carbon material can more easily occlude halogen simple substances or halides.

In the fourth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to third aspects, the carbon material is graphite, graphene, graphene oxide, reduced graphene oxide, carbon nanotube, fullerene, carbon. It may contain at least one selected from the group consisting of fiber, carbon black, soft carbon, hard carbon, mesoporous carbon and activated carbon.

In the fifth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to third aspects, the carbon material is at least selected from the group consisting of carbon black, vapor-grown carbon fibers and graphene. One may be included.

In the sixth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fifth aspects, the M may contain Y.

In the seventh aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to fifth aspects, the M may contain Y and Zr.

In the eighth aspect of the present disclosure, for example, in the positive electrode material according to any one of the first to seventh aspects, the X may contain at least one selected from the group consisting of Cl and Br. ..

According to the fourth to eighth aspects, the battery containing the positive electrode material has better charge / discharge characteristics.

The battery according to the ninth aspect of the present disclosure is
A positive electrode containing a positive electrode material according to any one of the first to eighth aspects, and a positive electrode.
With the negative electrode
An electrolyte layer arranged between the positive electrode and the negative electrode,
It has.

According to the ninth aspect, in the battery, the charge / discharge reaction proceeds by a new mechanism. Batteries tend to have high output.

In the tenth aspect of the present disclosure, for example, in the battery according to the ninth aspect, the negative electrode may contain a negative electrode active material capable of occluding lithium.

In the eleventh aspect of the present disclosure, for example, in the battery according to the ninth or tenth aspect, the negative electrode is a metallic lithium, a lithium alloy, a metallic indium, an indium alloy, a carbon material, a silicon, a silicon alloy, silicon oxide and a titanic acid. It may contain at least one selected from the group consisting of lithium.

According to the tenth or eleventh aspect, the battery has better charge / discharge characteristics.

In the twelfth aspect of the present disclosure, for example, in the battery according to any one of the ninth to eleventh aspects, the electrolyte layer may contain a solid electrolyte material, and the composition of the solid electrolyte material is the same. The composition may be different from the composition of the material represented by the composition formula (1).

In the thirteenth aspect of the present disclosure, for example, in the battery according to any one of the ninth to twelfth aspects, the electrolyte layer may contain a sulfide solid electrolyte.

According to the twelfth or thirteenth aspect, the battery has better charge / discharge characteristics.

In the 14th aspect of the present disclosure, for example, in the battery according to any one of the 9th to 13th aspects, the halogen element contained in the material represented by the composition formula (1) is oxidized at the time of charging. May produce at least one selected from the group consisting of a single halogen and a halide, and upon discharge, the halogen element contained in at least one selected from the group consisting of a single halogen and the halide is reduced. May be done. According to the fourteenth aspect, in the battery, the charge / discharge reaction proceeds by a new mechanism.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a cross-sectional view showing a schematic configuration of the positive electrode material 1000 according to the first embodiment.

The positive electrode material 1000 includes a material 100 represented by the following composition formula (1) and a carbon material 101. Material 100 may be a material known as a halide solid electrolyte. In the present specification, the material 100 may be referred to as a "halide material".
Li _a M _b X _c・・・ Equation (1)
Here, a, b, and c are values larger than 0, respectively. a, b and c may satisfy a + b <c. M contains at least one selected from the group consisting of metallic elements other than Li and metalloid elements. X contains a halogen element. The halogen element comprises, for example, at least one selected from the group consisting of F, Cl, Br and I.

In the present disclosure, the "metalloid element" is B, Si, Ge, As, Sb and Te. "Metallic elements" are all elements contained in groups 1 to 12 of the periodic table except hydrogen, as well as B, Si, Ge, As, Sb, Te, C, N, P, O, S and Se. It is all the elements contained in the 13th to 16th groups of the periodic table except for. That is, the "metalloid element" or "metal element" is a group of elements that can become cations when a halogen compound and an inorganic compound are formed.

The carbon material 101 can occlude at least one selected from the group consisting of elemental halogens and halides. In the present specification, "the carbon material occludes ..." means that the carbon material 101 takes in an element other than carbon from the outside of the carbon material 101 and retains the element on the surface or inside of the carbon material 101. Means to do. Further, the carbon material 101 may release at least one selected from the group consisting of occluded halogen simple substances and halides. "The carbon material releases ..." means that other elements occluded in the carbon material 101 are desorbed from the carbon material 101.

With the above configuration, a new positive electrode material can be realized. Further, according to this positive electrode material, it is possible to realize a battery in which the charge / discharge reaction proceeds by a mechanism different from that of the conventional lithium ion battery. The halide material does not have to contain sulfur.

Patent Document 1 discloses a lithium ion battery using a positive electrode containing a lithium-containing metal oxide, a negative electrode containing a carbon material, and a non-aqueous organic electrolytic solution as an electrolyte. In the battery of Patent Document 1, lithium ions are desorbed from the lithium-containing positive electrode oxide during charging. The lithium ions are solvated in the electrolytic solution and diffuse into the electrolytic solution. Lithium ions diffused in the electrolytic solution are occluded in the carbon material.

Patent Document 2 discloses a solid electrolyte material having a composition represented by _{Li 3} YBr _6. In this solid electrolyte material, halogens are strongly attracted to yttrium. As a result, the solid electrolyte material exhibits high ionic conductivity. In Patent Document 2, the ionic conductivity of the solid electrolyte material is used for charging and discharging the battery.

As a result of diligent studies, the present inventors have made _{a positive electrode in which a material represented by Li a} M _b X _c and a carbon material capable of occluding at least one selected from the group consisting of elemental halogens and halides are combined. It has been newly found that by using a material, a battery capable of reversible charging and discharging can be produced by a mechanism different from that of a conventional battery.

Charging and discharging of the battery containing the positive electrode material of the present embodiment is performed by the following mechanism. First, when the battery is charged, the halogen element contained in the material 100 is oxidized. At this time, lithium ions are released from the material 100 for charge compensation. Oxidation of the halogen element produces at least one selected from the group consisting of elemental halogens and halides. Halogen alone is, for example, a compound represented by _{X 2.} The halide is, for example, a compound represented by _{MX d.} Here, d is the same value as the valence of M. The generated halogen simple substance or halide is occluded in the carbon material 101. Lithium ions move, for example, in the electrolyte layer in the battery and are occluded in the negative electrode. Next, when the battery is discharged, the lithium ions occluded in the negative electrode are released from the negative electrode. Lithium ions move to the positive electrode through the electrolyte layer. At the positive electrode during discharge, the halogen alone or the halide is reduced with the acceptance of electrons. Specifically, the halogen element contained in at least one selected from the group consisting of elemental halogens and halides is reduced. The reduced halogen simple substance or halide reacts with the lithium ions transferred from the negative electrode and is released from the carbon material 101. According to the material 100 represented by the composition formula (1), changes in the internal structure of the positive electrode are suppressed during charging and discharging of the battery. For example, when the battery is charged, it is possible to prevent the formation of voids inside the positive electrode. As a result, it is presumed that a reversible charge / discharge reaction proceeds in the battery. In this embodiment, the material 100 and the carbon material 101 can function as the positive electrode active material.

In a lithium ion battery, in order for the desorption or insertion of lithium in the positive electrode and the negative electrode to proceed, it is necessary for the active material and the electrolyte to rapidly exchange electrons and lithium ions. For example, in a positive electrode, electrons and lithium ions are exchanged at a three-phase interface formed by a positive electrode active material, a conductive auxiliary agent, and an electrolyte. The positive electrode active material is, for example, an oxide that stores lithium ions. The conductive auxiliary agent has, for example, a function of assisting the conduction of electrons. The electrolyte is contained in, for example, the electrolyte or the electrolyte layer and can transport lithium ions. In the positive electrode active material of a lithium ion battery, for example, electrons are conducted by hopping conduction through a metal-oxygen-metal bond. In this case, the conductivity of electrons in the positive electrode active material is greatly affected by the electronic state of the metal ions contained in the positive electrode active material. For example, when the valence of metal ions is uniform in the positive electrode active material, the electron conductivity of the positive electrode active material decreases. That is, at the end of charging or the end of discharging of the battery, the electron conductivity of the positive electrode active material decreases.

In the positive electrode including the positive electrode material of the present embodiment, for example, electrons and lithium ions are exchanged at a two-phase interface formed by the carbon material 101 having high electron conductivity and the material 100 having high ionic conductivity. .. That is, the charge / discharge reaction proceeds using the two-phase interface. Therefore, the positive electrode material of the present embodiment is suitable for improving the current density of the battery.

In the Raman spectrum of the carbon material 101, to the peak intensity I _G appearing in the range of 1500 cm ^-1 or 1700 cm ^-1 or less, the ratio I _D intensity I _D of the peak appearing in the range of 1300 cm ^-1 or 1400 cm ^-1 or less / _IG is, for example, 0 or more and 2 or less.

According to the above configuration, the carbon material 101 can more easily occlude the halogen alone or the halide.

The Raman spectrum of the carbon material 101 can be obtained, for example, by laser Raman spectroscopy. Peak appearing at 1300 cm ^-1 or 1400 cm ^-1 in the range, for example, from the sp ³ carbon bonds. Peak appearing at 1500 cm ^-1 or 1700 cm ^-1 in the range, for example, from sp ² carbon bond. Therefore, the lower the ratio I _D / I _G, the carbon material 101 has a number of π electrons. When charging the battery containing the positive electrode material 1000 of the present embodiment, the generated halogen simple substance or halide tends to be attracted to the π electrons of the carbon material 101. Therefore, the lower the ratio I _D / I _G, the carbon material 101 can be easily occluded simple halogen or halide.

The ratio I _D / _IG may be 0 or more and 1.6 or less, 0 or more and 1.1 or less, 0 or more and 0.5 or less, and 0 or more and 0.1 or less. It may be.

The BET specific surface area of the carbon material 101 is, for example, greater than ^{5 m 2} g ^-1. The BET specific surface area of the carbon material 101 can be determined, for example, by the BET (Brunauer-Emmett-Teller) method by adsorbing nitrogen gas. The larger the BET specific surface area of the carbon material 101, the larger the area in which the carbon material 101 and the material 100 are in contact with each other. When the BET specific surface area of the carbon material 101 is ^{larger than 5 m 2} g ^-1 , the current density of the battery containing the positive electrode material 1000 tends to increase. The larger the BET specific surface area of the carbon material 101, the more easily the carbon material 101 can occlude the halogen simple substance or the halide. Further, according to the above configuration, a battery having better charge / discharge characteristics can be realized.

The BET specific surface area of the carbon material 101 ^{may be larger than 10 m 2} g ^-1 , may be larger than 14 m ² g ^-1 , may be 40 m ² g ^-1 or more, and may be 100 m ² g ^-1 or more. There may be. The upper limit of the BET specific surface area of the carbon material 101 is not particularly limited, and is, for example, 1000 m ² g ^-1 .

According to the above configuration, the current density of the battery containing the positive electrode material 1000 tends to improve. Further, according to the above configuration, a battery having better charge / discharge characteristics can be realized.

The shape of the carbon material 101 is not particularly limited, and is, for example, particulate. In the present disclosure, "particulate" includes needle-like, scaly, spherical and elliptical spheres. When the shape of the carbon material 101 is particulate (for example, spherical), the median diameter of the carbon material 101 is not particularly limited and may be 0.001 μm or more and 100 μm or less. When the median diameter of the carbon material 101 is 0.001 μm or more, the carbon material 101 and the material 100 can form a good dispersed state in the positive electrode material 1000. As a result, the charge / discharge characteristics of the battery containing the positive electrode material 1000 can be improved. When the median diameter of the carbon material 101 is 100 μm or less, the lithium diffusion rate in the carbon material 101 increases. This allows the battery to operate at high output.

The median diameter of the carbon material 101 may be smaller than 10 μm, smaller than 8 μm, 5 μm or less, 3 μm or less, or 1 μm or less. The lower limit of the median diameter of the carbon material 101 may be 0.01 μm.

According to the above configuration, a battery having better charge / discharge characteristics can be realized.

The median diameter of the carbon material 101 may be larger than the median diameter of the material 100 described later. As a result, the carbon material 101 and the material 100 can form a good dispersed state.

In the present specification, the median diameter means the particle size (d50) corresponding to the cumulative volume of 50%, which is obtained from the particle size distribution measured by the laser diffraction / scattering method on a volume basis.

The carbon material 101 includes, for example, graphite (graphite), graphene, graphene oxide, reduced graphene oxide (RGO), carbon nanotube (CNT), fullerene, carbon fiber, carbon black (CB), and soft carbon (graphitizable carbon). ), Hard carbon (non-graphitizable carbon), mesoporous carbon and at least one selected from the group consisting of activated carbon. Graphite may be natural graphite or artificial graphite such as highly oriented pyrolytic graphite (HOPG). Examples of carbon fibers include vapor-grown carbon fibers. The carbon black may be acetylene black (AB) or Ketjen black (KB). The carbon material may contain at least one selected from the group consisting of carbon black, vapor-grown carbon fibers and graphene.

The content of the carbon material 101 in the positive electrode material 1000 is not particularly limited, and may be 1% by weight or more, 5% by weight or more, 10% by weight or more, or 15% by weight. It may be the above. The upper limit of the content of the carbon material 101 is not particularly limited, and is, for example, 40% by weight. The higher the content of the carbon material 101, the larger the discharge capacity of the battery containing the positive electrode material 1000 tends to be.

M in the composition formula (1) may contain Y, and may contain Y and Zr.

X in the composition formula (1) may contain at least one selected from the group consisting of Cl and Br, and may contain both Cl and Br.

In the composition formula (1), a, b and c may satisfy 1 ≦ a ≦ 5, 0 <b ≦ 2 and 5.5 ≦ c ≦ 6.5, and 1.5 ≦ a ≦ 4. 5, 0.5 ≦ b ≦ 1.5 and c = 6 may be satisfied. a, b and c may satisfy the relationship of a + mb = c. Here, m is a valence of M. When M contains a plurality of kinds of elements, mb is the sum of the values obtained by multiplying the composition ratio of each element by the valence of the element. For example, when M contains the element M1 and the element M2, the composition ratio _{of the element M1 is b 1} , the valence of the element M1 is m ₁ , the composition ratio _{of the element M2 is b 2} , and the valence of the element M2. When is m ₂ , mb = m ₁ b ₁ + m ₂ b ₂ . When a plurality of valences of the element M can be considered, the above relational expression may be satisfied when those possible valences are used as m.

The shape of the material 100 is not particularly limited, and is, for example, in the form of particles. When the shape of the material 100 is particulate (for example, spherical), the median diameter of the material 100 may be 100 μm or less. When the median diameter of the material 100 is 100 μm or less, the material 100 and the carbon material 101 can form a good dispersed state in the positive electrode material 1000. This improves the charge / discharge characteristics of the battery. The median diameter of the material 100 may be 10 μm or less.

The content of the material 100 in the positive electrode material 1000 is not particularly limited, and may be 30% by weight or more, or 50% by weight or more. The upper limit of the content of the material 100 may be 95% by weight, 90% by weight, or 85% by weight.

The positive electrode material 1000 may further contain materials other than the material 100 and the carbon material 101. Other materials include positive electrode active materials, binders, conductive aids and the like.

Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxysulfides, and transition metal oxynitrides. Examples of the lithium-containing transition metal oxide include Li (NiCoAl) O ₂ , Li (NiCoMn) O ₂ , and LiCoO ₂ . In particular, when a lithium-containing transition metal oxide is used as the positive electrode active material, the average discharge voltage of the battery can be improved.

The positive electrode active material may contain lithium nickel cobalt manganate as the lithium-containing transition metal oxide. For example, the positive electrode active material may be Li (NiComn) O ₂ . According to the above configuration, the positive electrode material 1000 can further improve the energy density of the battery and the charge / discharge efficiency of the battery.

The binder is used, for example, to improve the adhesion between particles and the binding property of the materials constituting the positive electrode when a positive electrode is prepared from the positive electrode material 1000. Examples of the binder include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylic nitrile, polyacrylic acid, polyacrylic acid methyl ester, and polyacrylic acid ethyl ester. , Polyacrylic acid hexyl ester, polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene butadiene Examples include rubber and carboxymethyl cellulose. 2 selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid and hexadiene 2 Copolymers of more than seed materials can also be used as binders. A mixture of two or more selected from these materials may be used as a binder.

The conductive auxiliary agent can be used for the purpose of improving the electronic conductivity of the positive electrode material 1000. Examples of the conductive auxiliary agent include conductive fibers such as metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, and conductive metal oxides such as titanium oxide. , And conductive polymer compounds such as polyacetylene, polyaniline, polypyrrole, polythiophene and the like can be used. The conductive polymer compound is suitable for improving the electron conductivity and plasticity of the positive electrode formed from the positive electrode material 1000.

The content of the other material in the positive electrode material 1000 is not particularly limited, and may be 50% by weight or less, 30% by weight or less, 10% by weight or less, or 5% by weight. It may be as follows. The positive electrode material 1000 does not have to substantially contain other materials. In particular, the positive electrode material 1000 does not have to substantially contain the positive electrode active material as another material. In other words, the positive electrode material 1000 may substantially consist of the material 100 and the carbon material 101. By "substantially consisting of" is meant eliminating other components that alter the essential characteristics of the mentioned material. However, the positive electrode material 1000 may contain impurities in addition to the material 100 and the carbon material 101.

The positive electrode material 1000 may include particles of a plurality of materials 100, particles of a plurality of carbon materials 101, and particles of a plurality of positive electrode active materials.

<Manufacturing method of material represented by composition formula (1)>
In the first embodiment, the material 100 can be produced, for example, by the following method.

First, a raw material powder for a dual halide is prepared at a blending ratio according to the desired composition. The binary halide refers to a compound composed of two kinds of elements including a halogen element. For example, when Li ₃ YCl ₆ is prepared, the raw material powder of LiCl and the raw material powder of YCl ₃ are prepared at a molar ratio of 3: 1.

At this time, the elements of "M" and "X" in the above composition formula (1) are determined depending on the type of raw material powder. The values of "a", "b" and "c" in the above-mentioned composition formula (1) are determined by the type of raw material powder, the blending ratio and the synthesis process.

After sufficiently mixing the raw material powders, the raw material powders are mixed, crushed and reacted using the method of mechanochemical milling. After the raw material powder is sufficiently mixed, the raw material powder may be sintered in vacuum.

By these methods, a material 100 containing a crystal phase having the above-mentioned composition can be obtained.

The composition (crystal structure) of the crystal phase in the material 100 is determined by the reaction method and reaction conditions between the raw material powders.

(Embodiment 2)
Hereinafter, the second embodiment will be described. The description overlapping with the above-described first embodiment will be omitted as appropriate.

FIG. 2 is a cross-sectional view showing a schematic configuration of the battery 2000 according to the second embodiment.

The battery 2000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203.

The positive electrode 201 includes the positive electrode material 1000 according to the first embodiment described above.

The electrolyte layer 202 is arranged between the positive electrode 201 and the negative electrode 203.

According to the above configuration, in the battery 2000, the charge / discharge reaction proceeds by a new mechanism. Further, it is possible to suppress an increase in the reaction overvoltage of the battery 2000.

In the positive electrode 201, 5 ≦ v1 ≦ 95 may be satisfied with respect to the volume ratio “v1: 100−v1” between the carbon material 101 and the material 100. v1 represents the volume ratio of the carbon material 101 when the total volume of the carbon material 101 and the material 100 contained in the positive electrode 201 is defined as 100. When v1 satisfies 5 ≦ v1, sufficient battery energy density can be ensured. If v1 satisfies v1 ≦ 95, the battery can operate at high power.

The thickness of the positive electrode 201 may be 5 μm or more and 500 μm or less. When the thickness of the positive electrode 201 is 5 μm or more, sufficient energy density of the battery can be secured. When the thickness of the positive electrode 201 is 500 μm or less, the battery can operate at a high output.

The electrolyte layer 202 is a layer containing an electrolyte material. The electrolyte material contained in the electrolyte layer 202 is, for example, a solid electrolyte material. That is, the electrolyte layer 202 may be a solid electrolyte layer.

Examples of the solid electrolyte material contained in the electrolyte layer 202 include a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte. The electrolyte layer 202 may contain a sulfide solid electrolyte.

The composition of the solid electrolyte material contained in the electrolyte layer 202 may be the same as the composition of the material 100 of the positive electrode material 1000 in the above-described first embodiment. That is, the electrolyte layer 202 may include the material 100 according to the first embodiment described above as the solid electrolyte material.

According to the above configuration, the output density and charge / discharge characteristics of the battery can be further improved.

The composition of the solid electrolyte material contained in the electrolyte layer 202 may be different from the composition of the material 100 of the positive electrode material 1000 in the above-described first embodiment. The electrolyte layer 202 may contain, as the solid electrolyte material, a halide solid electrolyte having a composition different from that of the material 100 in the first embodiment described above.

According to the above configuration, the charge / discharge characteristics of the battery can be further improved.

Examples of the sulfide solid electrolyte include Li ₂ SP ₂ S ₅ , Li ₂ S-SiS ₂ , Li ₂ _{SB 2} S ₃ , Li ₂ S-GeS ₂ , Li _3.25 Ge _0.25 P _0.75 S ₄ , Li ₁₀ GeP ₂ S _{12 and the} like can be used. These sulfide solid _{electrolyte, LiX, Li 2 O, MO} q, like Li _p MO _q may be added. Here, X is at least one selected from the group consisting of F, Cl, Br and I. M is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe and Zn. p and q are natural numbers, respectively.

According to the above configuration, since the electrolyte layer 202 contains a sulfide solid electrolyte having excellent reduction stability, a low potential material such as graphite or metallic lithium can be used as the negative electrode material. Thereby, the energy density of the battery can be improved.

Examples of the oxide solid electrolyte include _{a NASICON type solid electrolyte typified by LiTi 2} (PO ₄ ) ₃ and its elemental substituent, a (LaLi) TiO ₃ based perovskite type solid electrolyte, Li ₁₄ ZnGe ₄ O ₁₆ , Li. ₄ SiO ₄ , LiGeO ₄ and LISION type solid electrolyte typified by its element substitution product, Li ₇ La ₃ Zr ₂ O ₁₂ and garnet type solid electrolyte typified by its element substitution product, Li ₃ N and its H substitution product , Li ₃ PO ₄ and its N-substituted products, and glass or glass ceramics based on Li-BO _{compounds such as Li BO 2} and Li ₃ _{BO 3} _{with added Li 2} SO ₄ , Li ₂ CO _{3 and the like.} Can be used.

As the polymer solid electrolyte, for example, a compound of a polymer compound and a lithium salt can be used. The polymer compound may have an ethylene oxide structure. The polymer compound having an ethylene oxide structure can contain a large amount of lithium salt. Therefore, the ionic conductivity of the electrolyte layer 202 can be further increased. The lithium _{_{salt, LiPF 6, LiBF 4, LiSbF}} 6, LiAsF 6, LiSO 3 CF 3, LiN (SO 2 CF 3) 2, LiN (SO 2 C 2 F 5) 2, LiN (SO 2 CF 3) ( SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) _{3 and the} like can be used. One lithium salt selected from the exemplified lithium salts can be used alone. A mixture of two or more lithium salts selected from the exemplified lithium salts may be used.

As the complex hydride solid electrolyte, for example, LiBH _4- LiI and LiBH _4- P ₂ S ₅ can be used.

The electrolyte layer 202 may contain a solid electrolyte material as a main component. That is, the electrolyte layer 202 may contain, for example, 50% by weight or more of the solid electrolyte material as a weight ratio with respect to the whole of the electrolyte layer 202.

The electrolyte layer 202 may contain, for example, 70% by weight or more of the solid electrolyte material as a weight ratio to the whole of the electrolyte layer 202.

The electrolyte layer 202 contains a solid electrolyte material as a main component, and may further contain unavoidable impurities, a starting material used when synthesizing the solid electrolyte material, by-products, decomposition products, and the like.

The electrolyte layer 202 may contain 100% by weight of the solid electrolyte material as a weight ratio to the whole of the electrolyte layer 202, excluding impurities that are unavoidably mixed, for example.

As described above, the electrolyte layer 202 may be substantially composed of only the solid electrolyte material.

The electrolyte layer 202 may contain two or more of the materials listed as solid electrolyte materials. For example, the electrolyte layer 202 may contain a halide solid electrolyte and a sulfide solid electrolyte.

The thickness of the electrolyte layer 202 may be 1 μm or more and 300 μm or less. When the thickness of the electrolyte layer 202 is 1 μm or more, the positive electrode 201 and the negative electrode 203 can be separated more reliably. When the thickness of the electrolyte layer 202 is 300 μm or less, the battery can operate at high output.

The electrolyte layer 202 may have a multilayer structure in which two or more layers having different compositions are laminated. For example, in the electrolyte layer 202, a layer containing a halide solid electrolyte and a layer containing a sulfide solid electrolyte may be laminated.

The negative electrode 203 includes a material having the property of occluding and releasing metal ions (for example, lithium ions). The negative electrode 203 contains, for example, a negative electrode active material. Specifically, the negative electrode 203 may contain a negative electrode active material that can occlude lithium. According to the above configuration, a battery having better charge / discharge characteristics can be realized.

As the negative electrode active material, a metal material, a carbon material, an oxide, a nitride, a tin compound, a silicon compound, etc. can be used. The metal material may be a single metal. The metal material may be an alloy. Examples of metallic materials include metallic lithium and lithium alloys. Examples of carbon materials include natural graphite, coke, developing carbon, carbon fibers, spherical carbon, artificial graphite, amorphous carbon and the like. From the viewpoint of the capacity density of the battery, silicon (Si), tin (Sn), a silicon compound and a tin compound can be used.

The negative electrode 203 may contain at least one selected from the group consisting of metallic lithium, lithium alloy, metallic indium, indium alloy, carbon material, silicon, silicon alloy, silicon oxide and lithium titanate as the negative electrode active material. good.

The negative electrode 203 may contain a solid electrolyte material. As the solid electrolyte material contained in the negative electrode 203, the solid electrolyte material exemplified as the material constituting the electrolyte layer 202 may be used. According to the above configuration, the lithium ion conductivity inside the negative electrode 203 can be improved, and the battery can operate at a high output.

The shape of the negative electrode active material is not particularly limited, and is, for example, particulate. When the shape of the negative electrode active material is particulate (for example, spherical), the median diameter of the negative electrode active material may be 0.1 μm or more and 100 μm or less. When the median diameter of the negative electrode active material is 0.1 μm or more, the negative electrode active material and the solid electrolyte material can form a good dispersed state in the negative electrode 203. This improves the charge / discharge characteristics of the battery. When the median diameter of the negative electrode active material is 100 μm or less, the diffusion rate of lithium in the negative electrode active material increases. This allows the battery to operate at high output.

In the negative electrode 203, the median diameter of the negative electrode active material may be larger than the median diameter of the solid electrolyte material. As a result, the negative electrode active material and the solid electrolyte material can form a good dispersed state.

In the negative electrode 203, 30 ≦ v2 ≦ 95 may be satisfied with respect to the volume ratio “v2: 100-v2” between the negative electrode active material and the solid electrolyte material. v2 represents the volume ratio of the negative electrode active material when the total volume of the negative electrode active material and the solid electrolyte material contained in the negative electrode 203 is defined as 100. When v2 satisfies 30 ≦ v2, sufficient battery energy density can be secured. If v2 satisfies v2 ≦ 95, the battery can operate at high power.

The thickness of the negative electrode 203 may be 10 μm or more and 500 μm or less. When the thickness of the negative electrode 203 is 10 μm or more, sufficient energy density of the battery can be secured. When the thickness of the negative electrode 203 is 500 μm or less, the battery can operate at a high output.

At least one selected from the group consisting of the electrolyte layer 202 and the negative electrode 203 may contain a binder for the purpose of improving the adhesion between the particles. The binder is used, for example, to improve the binding property of the material constituting the negative electrode 203. As the binder, for example, the binder described above for the positive electrode material 1000 can be used.

The negative electrode 203 may contain a conductive auxiliary agent for the purpose of improving electronic conductivity. Examples of the conductive auxiliary agent contained in the negative electrode 203 include graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black and Ketjen black, conductive fibers such as carbon fibers and metal fibers, and carbon fluoride. , Metal powders such as aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole and polythiophene can be used. .. When a carbon conductive auxiliary agent is used as the conductive auxiliary agent, the cost can be reduced.

Examples of the shape of the battery 2000 include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminated type.

Hereinafter, the details of the present disclosure will be described with reference to examples. The present disclosure is not limited to the following examples.

<< Example 1 >>
[Preparation of material represented by composition formula (1)]
_{LiCl, YCl 3} and YBr ₃ were weighed as raw material powders at a molar ratio of LiCl: YCl ₃ : YBr ₃ = 3.000: 0.333: 0.666 under an argon atmosphere having a dew point of −60 ° C. or lower. These raw material powders were crushed in a mortar and mixed. Next, the obtained mixture was calcined at 500 ° C. for 3 hours under an argon atmosphere. An electric furnace was used for firing. The resulting calcined product was crushed using a pestle and a mortar. As a result, a powder of the material represented by the composition formula (1) was obtained. In the present specification, the material obtained by the above method may be referred to as LYBC.

[Preparation of positive electrode material]
The powder of the material represented by the composition formula (1) and the powder of the carbon material were weighed at a mass ratio of 92.6: 7.4 under an argon atmosphere having a dew point of −60 ° C. or lower. As the carbon material, graphite having a median diameter of 3 μm was used. Next, a positive electrode material was prepared by mixing these materials using an agate mortar.

[Battery production]
In an outer cylinder having an insulating property, _{powders of Li 6} PS ₅ Cl and LYBC, which are sulfide solid electrolytes, and a positive electrode material were laminated in this order. The weight of Li ₆ PS ₅ Cl was 60 mg. The weight of LYBC was 20 mg. The weight of the positive electrode material was 5 mg. Next, a solid electrolyte layer and a first electrode, which is a positive electrode, were obtained by applying a pressure of 720 MPa to these materials.

Next, the metal In foil and the metal Li foil were laminated on the surface of the solid electrolyte layer opposite to the surface in contact with the first electrode. By applying a pressure of 80 MPa to these metal foils, a laminate composed of a first electrode, a solid electrolyte layer, and a second electrode as a negative electrode was produced.

Next, current collectors made of stainless steel were placed on each of the positive electrode and the negative electrode, and current collector leads were provided on these current collectors. Next, the battery of Example 1 was produced by blocking and sealing the inside of the insulating outer cylinder from the outside air atmosphere using an insulating ferrule.

[Charge / discharge test]
The battery of Example 1 was subjected to a charge / discharge test by the following method. First, the batteries were placed in a constant temperature bath set at 25 ° C. The battery was charged with a constant current at a current value of 0.05 mA. Charging was carried out until the voltage of the battery reached 4.0 V. Next, the battery was discharged at a current value of 0.05 mA. The discharge was carried out until the voltage of the battery reached 1.9 V.

<< Example 2 >>
Example by the same method as in Example 1 except that the positive electrode material was prepared by using the powder of the material represented by the composition formula (1) and the powder of the carbon material at a mass ratio of 83.0: 17.0. 2 batteries were produced. Further, a charge / discharge test was performed on the battery of Example 2 by the same method as in Example 1.

<< Example 3 >>
Example by the same method as in Example 1 except that the positive electrode material was prepared by using the powder of the material represented by the composition formula (1) and the powder of the carbon material in a mass ratio of 76.5: 23.5. 3 batteries were produced. Further, a charge / discharge test was performed on the battery of Example 3 by the same method as in Example 1.

<< Example 4 >>
In the production of the positive electrode material, the battery of Example 4 was produced by the same method as in Example 1 except that acetylene black was used as the carbon material. Further, a charge / discharge test was performed on the battery of Example 4 by the same method as in Example 1.

<< Example 5 >>
In the production of the positive electrode material, the battery of Example 5 was produced by the same method as in Example 1 except that carbon black was used as the carbon material. Further, a charge / discharge test was performed on the battery of Example 5 by the same method as in Example 1.

<< Example 6 >>
In the production of the positive electrode material, the battery of Example 6 was produced by the same method as in Example 1 except that the vapor-grown carbon fiber (VGCF (registered trademark)) was used as the carbon material. Further, a charge / discharge test was performed on the battery of Example 6 by the same method as in Example 1.

<< Example 7 >>
In the production of the positive electrode material, the battery of Example 7 was produced by the same method as in Example 1 except that graphene was used as the carbon material. Further, a charge / discharge test was performed on the battery of Example 7 by the same method as in Example 1.

<< Example 8 >>
In the production of the positive electrode material, the battery of Example 8 was produced by the same method as in Example 4 except that _{Li 3} YBr ₆ was used as the material represented by the composition formula (1). In Example 8, a battery used for the charge / discharge test and a battery used for the cyclic voltammetry measurement described later were prepared. Li ₃ YBr ₆ was prepared by the following method. _{First, LiBr and YBr 3} were weighed as raw material powders at a molar ratio of LiBr: YBr ₃ = 3: 1 in an argon glove box having a dew point of −60 ° C. or lower. Next, the mixture of these raw material powders was milled for 25 hours at a rotation speed of 600 rpm using a planetary ball mill (manufactured by Fritsch, P-7 type). As a result, a powder of _{Li 3} YBr _{6 was obtained.} In the present specification, Li ₃ YBr ₆ may be referred to as LYB. Further, a charge / discharge test was performed on the battery of Example 8 by the same method as in Example 1.

For the battery of Example 8, cyclic voltammetry (CV) measurement was also performed by the following method. First, the batteries were placed in a constant temperature bath set at 25 ° C. A battery was connected to the potencio galvanostat and CV measurements were taken. In the CV measurement, the sweep speed was set to 10 mV / s. The scanning range is 4.0 V to 1.9 V vs. It was set to In-Li.

<< Example 9 >>
In the production of the positive electrode material, the battery of Example 9 was produced by the same method as in Example 4 except that _{Li 2.7} Y _1.1 Cl ₆ was used as the material represented by the composition formula (1). In Example 9, a battery used for the charge / discharge test and a battery used for the CV measurement were prepared. Li _2.7 Y _1.1 Cl ₆ was prepared by the following method. _{First, LiCl and YCl 3} were weighed as raw material powders at a molar ratio of LiCl: YCl ₃ = 2.7: 1.1 in an argon glove box having a dew point of −60 ° C. or lower. Next, the mixture of these raw material powders was milled for 25 hours at a rotation speed of 600 rpm using a planetary ball mill (manufactured by Fritsch, P-7 type). As a result, a powder of _{Li 2.7} Y _1.1 Cl _{6 was obtained.} In the present specification, Li _2.7 Y _1.1 Cl ₆ may be referred to as LYC. Further, a charge / discharge test was performed on the battery of Example 9 by the same method as in Example 1. CV measurement was performed on the battery of Example 9 by the same method as in Example 8.

<< Example 10 >>
In the production of the positive electrode material, the battery of Example 10 was produced by the same method as in Example 4 except that _{Li 2.5} Y _0.5 Zr _0.5 Cl ₆ was used as the material represented by the composition formula (1). Li _2.5 Y _0.5 Zr _0.5 Cl ₆ was prepared by the following method. _{First, LiCl, YCl 3} and ZrCl ₄ are weighed as raw material powders at a molar ratio of LiCl: YCl ₃ : ZrCl ₄ = 2.5: 0.5: 0.5 in an argon glove box having a dew point of -60 ° C or lower. bottom. Next, the mixture of these raw material powders was milled for 25 hours at a rotation speed of 600 rpm using a planetary ball mill (manufactured by Fritsch, P-7 type). As a result, a powder of _{Li 2.5} Y _0.5 Zr _0.5 Cl _{6 was obtained.} In the present specification, Li _2.5 Y _0.5 Zr _0.5 Cl ₆ may be referred to as LYZC. Further, a charge / discharge test was performed on the battery of Example 10 by the same method as in Example 1.

≪Reference example 1≫
[Preparation of positive electrode material]
In an argon glove box having a dew point of −60 ° C. or lower, LiBr, LiCl and a carbon material were weighed as raw material powders at a mass ratio of LiBr: LiCl: carbon material = 29:29:42. As the carbon material, graphite having a median diameter of 8 μm was used. Next, these raw material powders were mixed using a planetary ball mill (P-7 type manufactured by Fritsch). Mixing with a planetary ball mill was performed at a rotation speed of 200 rpm for 10 minutes, a rotation speed of 400 rpm for 30 minutes, and a rotation speed of 500 rpm for 30 minutes.

_{Next, the obtained mixture and Li 6} PS ₅ Cl, which is a sulfide solid electrolyte, were weighed at a mass ratio of 74.8: 25.2 under an argon atmosphere having a dew point of −60 ° C. or lower. Next, a positive electrode material was prepared by mixing these materials using an agate mortar.

[Battery production]
The battery of Reference Example 1 was produced by the same method as in Example 1 except that the above positive electrode material was used.

[Charge / discharge test]
A charge / discharge test was performed on the battery of Reference Example 1 by the same method as in Example 1 except that the cutoff voltage was set to 3.6 V.

≪Reference example 2≫
In the preparation of the positive electrode material, the powder of metal Al was used instead of the carbon material, and the powder of the material represented by the composition formula (1) and the powder of metal Al were used at a mass ratio of 90:10. Except for the above, the battery of Reference Example 2 was produced by the same method as in Example 1. Further, a charge / discharge test was performed on the battery of Reference Example 2 by the same method as in Example 1.

Table 1 shows the results of the battery charge / discharge tests of Examples and Reference Examples. Table 1, the type of the carbon material contained in the positive electrode, the content of the carbon material in the positive electrode, the median size of the ratio I _D / I _G, the carbon material in the carbon material, BET specific surface area of the carbon material, the composition formula (1) The types of materials represented by are also shown. The ratio I _D / I _G in the carbon material, as described above, in the Raman spectrum of the carbon material, to the intensity I _G of the peak appearing in the range of 1500 cm ^-1 or 1700 cm ^-1 or less, 1300 cm ^-1 or 1400 cm ^-1 or less It means the ratio _{of the intensity ID} of the peaks appearing in the range of. The ratio I _D / I _G, median diameter and BET specific surface area is a value measured for the carbon material prior to making the cathode material. In the charge / discharge test, it was evaluated that the battery that reached the cutoff voltage immediately after the start of charging and the battery that reached the cutoff voltage quickly after the start of discharge while the current flowed during charging could not be charged / discharged. ..

<Discussion>
FIG. 3 is a graph showing the initial charge / discharge curves of the batteries of Examples 1, 2 and 3. FIG. 3 shows the discharge characteristics of the battery.

In the charge / discharge test of Example 1, first, the battery voltage is 4.0 Vvs., Which is the cutoff voltage from the open circuit voltage. A constant current was applied in the forward direction from the negative electrode to the positive electrode until In-Li was reached. Next, the voltage of the battery is the cutoff voltage of 1.9 Vvs. A constant current was applied in the direction opposite to that during charging until In-Li was reached. As shown in FIG. 3, in the charge / discharge test of Example 1, a plateau region associated with the charge / discharge of the battery was observed. Further, as can be seen from the comparison of Examples 1 to 3, the higher the content of the carbon material in the positive electrode, the greater the amount of electricity due to charging and discharging.

Since the plateau region was observed by the charge / discharge test, it can be seen that the battery of Example 1 behaves differently from the capacitor. In capacitors, the voltage tends to rise linearly with respect to the current. Since the plateau region was observed, it is presumed that in the battery of Example 1, an electrochemical redox reaction occurred during the charge / discharge test. That is, it can be seen that the charging reaction proceeded by passing the current in the forward direction, and the discharge reaction proceeded by passing the current in the reverse direction. Furthermore, the higher the content of the carbon material in the positive electrode, the greater the amount of electricity due to charging and discharging. Therefore, it is estimated that the carbon material and the material represented by the composition formula (1) have reacted electrochemically. Will be done. In Example 1, since an In—Li alloy is used as the negative electrode and the reversible charge / discharge reaction is proceeding, it can be seen that the charge carriers are Li ions. That is, in the battery of Example 1, Li ions, which are charge carriers, move from the positive electrode to the negative electrode via the solid electrolyte layer during charging.

FIG. 4 is a graph showing the initial charge / discharge curves of the batteries of Reference Examples 1 and 2.

In Reference Example 1, a mixture of LiBr and LiCl was used instead of the material represented by the composition formula (1). In the mixture, the molar ratio of Br to Cl was 1: 2. This mixture and the carbon material were mixed well using a ball mill. A positive electrode material was prepared by further mixing the mixture thus obtained with a sulfide solid electrolyte having Li ion conductivity. In the battery charge / discharge test of Reference Example 1, a charging curve indicating that the charging of the battery has progressed was confirmed. However, the battery of Reference Example 1 could not be discharged.

In Reference Example 2, a positive electrode material was prepared by mixing the material represented by the composition formula (1) used in Example 1 with the powder of metallic Al. In the battery charge / discharge test of Reference Example 2, no current flowed through the battery during both charging and discharging, and the battery voltage reached the cutoff voltage.

From the above results, it can be seen that in order for the charging reaction to proceed in the battery, it is necessary to combine the material represented by the composition formula (1) and the carbon material. Further, it can be seen that in order for the discharge reaction to proceed, at least one selected from the group consisting of metal elements other than Li and metalloid elements is required in the material represented by the composition formula (1).

The detailed mechanism is currently under investigation, but it is said that the contact between the carbon material and the material represented by the composition formula (1) promotes the redox reaction of the material represented by the composition formula (1). Presumed. Further, it is known that a carbon material having a layered structure such as graphite can adsorb various elements in the layered structure. From this, in the positive electrode including the carbon material and the material represented by the composition formula (1), the carbon material occludes the halogen simple substance or the halide generated by the redox reaction of the material represented by the composition formula (1). It is presumed that it is. It is presumed that the function of this carbon material causes a reversible charge / discharge reaction to proceed in the battery.

Since the material represented by the composition formula (1) contains a metal element or a metalloid element other than Li, halogen gas is less likely to be generated by oxidation of the halogen element contained in the material when charging the battery. Therefore, when the battery is charged, voids are less likely to occur inside the positive electrode. That is, the internal structure of the positive electrode is unlikely to change. As a result, it is presumed that the conduction of electrons and lithium ions is less likely to be hindered during charging / discharging of the battery, and a reversible charging / discharging reaction proceeds. In Reference Example 1, it is presumed that the internal structure of the positive electrode changed when the battery was charged, so that the conduction of electrons and lithium ions was inhibited and the discharge reaction did not proceed.

FIG. 5 is a graph showing the initial charge / discharge curves of the batteries of Examples 4 to 7.

As can be seen from FIG. 5, a reversible charge / discharge reaction proceeded in the battery even when a carbon material other than graphite was used. The carbon materials used in Examples 4 to 7 include a graphite-like structure, a diamond-like structure, and the like. In the batteries of Examples 4 to 7, it is presumed that the charge / discharge reaction proceeded due to the graphite-like structure contained in the carbon material. That is, in the batteries of Examples 4 to 7, it is presumed that the charge / discharge reaction proceeded due to the layer structure contained in the carbon material. As can be seen from the comparison between Example 1 and Examples 4 to 7, carbon black such as acetylene black, vapor-grown carbon fibers and graphene are suitable for improving the discharge capacity of the battery as compared with graphite. ..

FIG. 6 is a graph showing the initial charge / discharge curves of the batteries of Examples 4, 8 and 9.

Even when LYB or LYC was used as the material represented by the composition formula (1), the reversible charge / discharge reaction proceeded in the battery as in the case of using LYBC. From this result, it can be seen that the material represented by the composition formula (1) does not have to contain both Br and Cl, and may contain only one kind of halogen element. In particular, it is presumed that the type of halogen element contained in the material represented by the composition formula (1) is not limited to Br or Cl as long as the voltage of the battery can be swept to the voltage at which the redox of the halogen element occurs.

FIG. 7 is a graph showing the cyclic voltammograms of the batteries of Examples 9, 10 and Reference Example 2.

As can be seen from FIG. 7, in the battery of Reference Example 2, no peak due to redox of the material represented by the composition formula (1) was observed. From this, it can be seen that the redox reaction of the material represented by the composition formula (1) hardly proceeds in the combination of the metal Al and the material represented by the composition formula (1).

On the other hand, as can be seen from FIG. 7, in the batteries of Examples 9 and 10, the peak caused by the redox of the material represented by the composition formula (1) could be clearly observed. From this, it can be seen that the redox reaction of the material proceeds even when LYC or LYZC is used as the material represented by the composition formula (1). That is, it can be seen that the redox reaction of the material proceeds regardless of the types of metal elements and metalloid elements other than Li contained in the material represented by the composition formula (1). It can be seen that regardless of the types of metal elements and metalloid elements other than Li contained in the material represented by the composition formula (1), the halogen simple substance or the halide generated from the material is occluded in the carbon material.

<< Example 11 >>
[Preparation of material represented by composition formula (1)]
By the same method as in Example 1, a powder of LYBC, which is a material represented by the composition formula (1), was obtained.

[Preparation of positive electrode material]
The LYBC powder and the graphene powder, which is a carbon material, were weighed at a mass ratio of 92.6: 7.4 under an argon atmosphere having a dew point of −60 ° C. or lower. Next, a positive electrode material was prepared by mixing these materials using an agate mortar.

Next, a metal Li foil was laminated on the surface of the solid electrolyte layer opposite to the surface in contact with the first electrode. By applying a pressure of 80 MPa to this metal foil, a laminate composed of a first electrode, a solid electrolyte layer, and a second electrode as a negative electrode was produced.

Next, current collectors made of stainless steel were placed on each of the positive electrode and the negative electrode, and current collector leads were provided on these current collectors. Next, the battery of Example 11 was produced by blocking and sealing the inside of the insulating outer cylinder from the outside air atmosphere using an insulating ferrule.

[Charging test]
The battery of Example 11 was charged by the following method. First, the batteries were placed in a constant temperature bath set at 25 ° C. The battery was charged with a constant current at a current value of 0.1 mA. Constant current charging was performed until the battery voltage reached 4.4 V. Next, the battery was charged at a constant voltage until the current value dropped to 0.01 mA.

[Discharge test]
A constant current-constant voltage charged battery was discharged at a constant current value of 0.01 mA. Constant current discharge was performed until the battery voltage reached 2.5 V. Next, the battery was discharged at a constant voltage until the current value dropped to 0.002 mA.

[Raman spectroscopy]
Raman spectroscopic measurements were performed on the positive electrode material of the battery of Example 11 before the charge test, after the charge test, and after the discharge test. Raman spectroscopy was performed by the following method. First, the above-mentioned laminate was taken out from the battery. Next, Raman spectroscopic measurement was performed with the laminated body enclosed in an airtight cell. Raman spectroscopic measurement was performed using an NRS-5500 manufactured by JASCO Corporation with an Ar ion laser that emits light having a wavelength of 457 nm. Specifically, the surface of the laminate on the positive electrode side was mapped and measured. Carbon-derived peaks were separated from the obtained data by performing a multivariate spectrum analysis (MCR) method. As a result, a Raman spectrum of the carbon material in the positive electrode material was obtained.

FIG. 8 is a graph showing the results of Raman spectroscopic measurement of the positive electrode material of the battery of Example 11 before the charge test, after the charge test, and after the discharge test. The graph in FIG. 8 also shows the results of Raman spectroscopic measurements on graphene powder. As can be seen from FIG. 8, in the Raman spectrum of the carbon material in the positive electrode material after the charging test, the G band peak appearing near ^{1580 cm -1 is broader than the Raman spectrum of the carbon material in the positive electrode material before the charging test.} It became, and it was shifting to the high wave number side. From this, it is presumed that the carbon material adsorbed the halogen simple substance or the halide derived from the material represented by the composition formula (1) by the charging test.

Further, as can be seen from FIG. 8, in the Raman spectrum of the carbon material in the positive electrode material after the discharge test, the peak of the G band shifts to the low wavenumber side as compared with the Raman spectrum of the carbon material in the positive electrode material after the charge test. Was. From this, it is presumed that the halogen simple substance or the halide adsorbed on the carbon material was desorbed from the carbon material by the discharge test.

The positive electrode material of the present disclosure can be used, for example, in an all-solid-state secondary battery.

Claims

The material represented by the following composition formula (1) and
A carbon material capable of occluding at least one selected from the group consisting of elemental halogens and halides,
Including positive electrode material.
Li a M b X c・・・ Equation (1)
Here, a, b, and c are values larger than 0, respectively.
M contains at least one selected from the group consisting of metallic elements other than Li and metalloid elements.
X contains a halogen element.
In the Raman spectrum of the carbon material, to the peak intensity I G appearing in the range of 1500 cm -1 or 1700 cm -1 or less, the ratio I D intensity I D of the peak appearing in the range of 1300 cm -1 or 1400 cm -1 or less The positive electrode material according to claim 1, wherein / IG is 0 or more and 2 or less.
The positive electrode material according to claim 1 or 2, wherein the carbon material has a BET specific surface area of more than 5 m 2 g -1.
The carbon material comprises at least one selected from the group consisting of graphite, graphene, graphene oxide, reduced graphene oxide, carbon nanotubes, fullerene, carbon fiber, carbon black, soft carbon, hard carbon, mesoporous carbon and activated carbon. , The positive electrode material according to any one of claims 1 to 3.
The positive electrode material according to any one of claims 1 to 3, wherein the carbon material contains at least one selected from the group consisting of carbon black, vapor-grown carbon fibers and graphene.
The positive electrode material according to any one of claims 1 to 5, wherein M contains Y.
The positive electrode material according to any one of claims 1 to 5, wherein M contains Y and Zr.
The positive electrode material according to any one of claims 1 to 7, wherein X comprises at least one selected from the group consisting of Cl and Br.
A positive electrode containing the positive electrode material according to any one of claims 1 to 8.
With the negative electrode
An electrolyte layer arranged between the positive electrode and the negative electrode,
With a battery.
The battery according to claim 9, wherein the negative electrode contains a negative electrode active material capable of occluding lithium.
9. or 10, wherein the negative electrode comprises at least one selected from the group consisting of metallic lithium, lithium alloy, metallic indium, indium alloy, carbon material, silicon, silicon alloy, silicon oxide and lithium titanate. Battery.
The electrolyte layer contains a solid electrolyte material and contains
The battery according to any one of claims 9 to 11, wherein the composition of the solid electrolyte material is different from the composition of the material represented by the composition formula (1).
The battery according to any one of claims 9 to 12, wherein the electrolyte layer contains a sulfide solid electrolyte.
At the time of charging, the halogen element contained in the material represented by the composition formula (1) is oxidized to generate at least one selected from the group consisting of simple substances of halogen and halides.
The battery according to any one of claims 9 to 13, wherein the halogen element contained in at least one selected from the group consisting of the halogen simple substance and the halide is reduced at the time of discharge.